This a renewal T32 application for graduate student training in immunolgy, microbial sciences, and related topics at The Scripps Research Institute (TSRI). This program is currently in its 10th year. The present proposal includes a larger faculty base than in the past (42 laboratories drawn from a total of 289 faculty members), reflecting the merger of the former Immunology Department with other faculty into the Department of Immunology and Microbial Science, and outreach to all departments at TSRI, including Genetics, Molecular Biology, Cell Biology, Chemical Biology and Chemistry. The wider scope reflects both the growth of our institution and the multidisciplinary nature of science at TSRI. The proposed support shall be available to students at TSRI regardless of department affiliation, provided that their research is related to immunology, microbiology, or host defense. This training program is part of a highly successful Doctoral Programs in Chemical and Biological Sciences. The TSRI graduate program attracts top-notch applicants and has been successful in training high quality scientists who have continued research careers. During the previous award period, all positions have been filled with talented individuals. TSRI is the largest non-profit research organization in the country, offering world-class research facilities. The faculty mentors in this training program are at the forefront of research into the mechanisms involved in generating and regulating immune responses, including responses of both the adaptive and innate arms of the immune system. In partial recognition of these achievements, this year two of our participating faculty members, Bruce Beutler and Michael Oldstone, were elected to the National Academy of Sciences. The unusually wide diversity of areas of investigation within the Training Program, from basic science to clinical applications as well as bioterrorism-related research, affords excellent opportunities for graduate student research and training in Immunology. Participation in scientific meetings, research-in-progress seminars, journal clubs, and lecture series gives students exposure to a multitude of different disciplines and experience in presenting their research to others.